[PATCH 6.1 0718/1146] misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and gru_handle_user_call_os

Greg Kroah-Hartman
2022-12-28T16:24:41Z

From: Zheng Wang <zyytlz.wz@163.com>

[ Upstream commit 643a16a0eb1d6ac23744bb6e90a00fc21148a9dc ]

In some bad situation, the gts may be freed gru_check_chiplet_assignment.
The call chain can be gru_unload_context->gru_free_gru_context->gts_drop
and kfree finally. However, the caller didn't know if the gts is freed
or not and use it afterwards. This will trigger a Use after Free bug.

Fix it by introducing a return value to see if it's in error path or not.
Free the gts in caller if gru_check_chiplet_assignment check failed.

Fixes: 55484c45dbec ("gru: allow users to specify gru chiplet 2")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Link: https://lore.kernel.org/r/20221110035033.19498-1-zyytlz.wz@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/misc/sgi-gru/grufault.c | 13 +++++++++++--
drivers/misc/sgi-gru/grumain.c | 22 ++++++++++++++++++----
drivers/misc/sgi-gru/grutables.h | 2 +-
3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index d7ef61e602ed..b836936e9747 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -648,6 +648,7 @@ int gru_handle_user_call_os(unsigned long cb)
if ((cb & (GRU_HANDLE_STRIDE - 1)) || ucbnum >= GRU_NUM_CB)
return -EINVAL;

+again:
gts = gru_find_lock_gts(cb);
if (!gts)
return -EINVAL;
@@ -656,7 +657,11 @@ int gru_handle_user_call_os(unsigned long cb)
if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE)
goto exit;

- gru_check_context_placement(gts);
+ if (gru_check_context_placement(gts)) {
+ gru_unlock_gts(gts);
+ gru_unload_context(gts, 1);
+ goto again;
+ }

/*
* CCH may contain stale data if ts_force_cch_reload is set.
@@ -874,7 +879,11 @@ int gru_set_context_option(unsigned long arg)
} else {
gts->ts_user_blade_id = req.val1;
gts->ts_user_chiplet_id = req.val0;
- gru_check_context_placement(gts);
+ if (gru_check_context_placement(gts)) {
+ gru_unlock_gts(gts);
+ gru_unload_context(gts, 1);
+ return ret;
+ }
}
break;
case sco_gseg_owner:
diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 6706ef3c5977..4eb4b9455139 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -716,9 +716,10 @@ static int gru_check_chiplet_assignment(struct gru_state *gru,
* chiplet. Misassignment can occur if the process migrates to a different
* blade or if the user changes the selected blade/chiplet.
*/
-void gru_check_context_placement(struct gru_thread_state *gts)
+int gru_check_context_placement(struct gru_thread_state *gts)
{
struct gru_state *gru;
+ int ret = 0;

/*
* If the current task is the context owner, verify that the
@@ -726,15 +727,23 @@ void gru_check_context_placement(struct gru_thread_state *gts)
* references. Pthread apps use non-owner references to the CBRs.
*/
gru = gts->ts_gru;
+ /*
+ * If gru or gts->ts_tgid_owner isn't initialized properly, return
+ * success to indicate that the caller does not need to unload the
+ * gru context.The caller is responsible for their inspection and
+ * reinitialization if needed.
+ */
if (!gru || gts->ts_tgid_owner != current->tgid)
- return;
+ return ret;

if (!gru_check_chiplet_assignment(gru, gts)) {
STAT(check_context_unload);
- gru_unload_context(gts, 1);
+ ret = -EINVAL;
} else if (gru_retarget_intr(gts)) {
STAT(check_context_retarget_intr);
}
+
+ return ret;
}

@@ -934,7 +943,12 @@ vm_fault_t gru_fault(struct vm_fault *vmf)
mutex_lock(&gts->ts_ctxlock);
preempt_disable();

- gru_check_context_placement(gts);
+ if (gru_check_context_placement(gts)) {
+ preempt_enable();
+ mutex_unlock(&gts->ts_ctxlock);
+ gru_unload_context(gts, 1);
+ return VM_FAULT_NOPAGE;
+ }

if (!gts->ts_gru) {
STAT(load_user_context);
diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h
index 8c52776db234..640daf1994df 100644
--- a/drivers/misc/sgi-gru/grutables.h
+++ b/drivers/misc/sgi-gru/grutables.h
@@ -632,7 +632,7 @@ extern int gru_user_flush_tlb(unsigned long arg);
extern int gru_user_unload_context(unsigned long arg);
extern int gru_get_exception_detail(unsigned long arg);
extern int gru_set_context_option(unsigned long address);
-extern void gru_check_context_placement(struct gru_thread_state *gts);
+extern int gru_check_context_placement(struct gru_thread_state *gts);
extern int gru_cpu_fault_map_id(void);
extern struct vm_area_struct *gru_find_vma(unsigned long vaddr);
extern void gru_flush_all_tlb(struct gru_state *gru);
--
2.35.1